Test TC-156A - Downstream O2 Sensor Shorted To Ground
NOTE:
For connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS
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- This Diagnostic Trouble Code (DTC) may be stored in Powertrain Control Module (PCM) if downstream oxygen sensor signal voltage is less than .078 volt prior to downstream oxygen sensor heater test, and downstream oxygen sensor signal voltage is less than .078 volt after ignition is turned on in subsequent start. Possible causes are: dirt/moisture or grease on connector causing voltage tracking, sensor signal wire shorted to another circuit, defective downstream oxygen sensor, defective connector terminals or wiring, defective PCM. Downstream oxygen sensor is mounted on exhaust pipe, behind catalytic converter. Go to next step.
- Turn ignition on with engine off. Using scan tool, monitor downstream oxygen sensor voltage for a few minutes. Wait 3 minutes or until downstream oxygen sensor voltage stabilizes, and then note downstream oxygen sensor voltage.
- If downstream oxygen sensor voltage is less than .078 volt, go to next step. If downstream oxygen sensor voltage is .078 volt or more, conditions required to set DTC are not present at this time. Perform TEST VER-5A - ROAD TEST FOR OBD-II TROUBLE CODES .
- Turn ignition off. Disconnect connector at downstream oxygen sensor. Turn ignition on. Using scan tool, monitor downstream oxygen sensor voltage.
- If downstream oxygen sensor voltage is less than .078 volt, go to next step. If downstream oxygen sensor voltage is .078 volt or more, replace downstream oxygen sensor. Perform TEST VER-5A - ROAD TEST FOR OBD-II TROUBLE CODES .
- Turn ignition off. Disconnect connectors from PCM. The PCM is located between driver's side front fender and power distribution center, near battery.
- Using ohmmeter, check resistance between terminals No. 3 (Black/Light Blue wire) and No. 4 (Tan/White wire) at wiring harness side of connector for downstream oxygen sensor. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short between Tan/White wire and Black/Light Blue wire from PCM to downstream oxygen sensor. Perform TEST VER-5A - ROAD TEST FOR OBD-II TROUBLE CODES .
- Using ohmmeter, check resistance between ground and terminal No. 4 (Tan/White wire) at wiring harness side of connector for downstream oxygen sensor. If resistance is 5 ohms or more, replace PCM. Perform TEST VER-5A - ROAD TEST FOR OBD-II TROUBLE CODES . If resistance is less than 5 ohms, repair short to ground on Tan/White wire between PCM and downstream oxygen sensor. Perform TEST VER-5A - ROAD TEST FOR OBD-II TROUBLE CODES .